The accurate identification of product ion spectra (MS/MS) or precursor ion mass to charge ratio (mass fingerprinting) is predicated on the ability of a de-isotoping algorithm to correctly assign the charge state (z) of ions and determine the lowest mass peak A0 of an isotopic distribution (also known as the monoisotopic mass).
Due to the lack of elemental variability in biomolecules (peptide, lipids, metabolites etc.) the process of seeking to determine the charge state of the ions and determine the lowest mass peak A0 of an isotopic distribution can be particularly problematic when analysing either a simple or a complex biomolecule mixture since certain mass to charge ratio values can exist at multiple charge states.
Furthermore, there can be both inter-digitated and overlapping ion clusters which will cause significant problems for the de-isotoping algorithm to resolve.
It is desired to provide an improved method of mass spectrometry.